Sine bar assembly



Sept. 5, 1961 s. PERGANDE 2,993,657

SINE BAR ASSEMBLY Filed Aug. 2, 1957 4 Sheets-Sheet 1 T 7 I 7 a g g4 6E 4 g 72 g V INVENTOR. z w las''e fifizya zde Sept. 5, 1961 L. s. PERGANDE SINE BAR ASSEMBLY 4 Sheets-Sheet 2 Filed Aug. 2, 1957 Q "MAE 4 Sheets-$heet 3 Sept. 5, 1961 s. PERGANDE SINE BAR ASSEMBLY Filed Aug. 2, 1957 Sept. 5, 1961 s. PERGANDE 2,998,657

SINE BAR ASSEMBLY Filed Aug. 2, 1957 4 Sheets-Sheet 4 INVENTOR.

United States Pate-m0."

1 2,998,657 SINE BAR ASSEMBLY Leslie S. Pergande, Mount Prospect, Ill., assignor to Illinois Tool Works, Chicago, Ill., a corporation of Illinois Filed Aug. 2, 1957, Ser. No. 675,856

1 Claim. (Cl. 33-4795) This invention is concerned with an improved sine bar assembly.

Sine bar assemblies are used in many precision measuring devices, a typical use being in machines for testing helical lead.

In the past, sine bars have been utilized in measuring machines only with a certain amount of difiiculty. It. has been very diflicult to position the sine bar in proper a'ngu lar relation to the slide of the machine with the requisite accuracy. To position such sine bars, it has been customary to use jo blocks, diamond scribed indicator plates, micrometer bits, etc. These have proven a considerable source of trouble due to their lack of accuracy, and the dependence on the skill of the operator.

Accordingly, it is an object of this invention to provide a sine bar assembly capable of more accurate positioning than heretofore thought possible.

More particularly, it is an object of this invention to provide a sine bar assembly capable of extremely rapid and very precise positioning. c

In addition, it is an object of this invention to provide a sine bar assembly which is rapidly motor driven to approximate setting, and then is finally adjusted by hand.

Other and further objects and advantages of the present invention will be apparent from the following-description when taken in connection with (the accompanying drawings wherein,

FIG. 1 is a perspective view of a lead checking ma chine incorporating the principles of this invention;

FIG. 2 is a vertical cross-sectional view through the headstock of the machine as taken along the line 2-2 in FIG. 1; 7

FIG. 3 is a vertical cross-sectional view as taken along the ,line 3-3 in FIG. 2; I

FIG. 4'is a cross-sectional view through an optical reading device of the machine as taken along the line 4-4 in FIG. 1;

FIG. 5 is. a front plan view, with certain parts being broken away for clarity of illustration;

: FIG." 6 is a right end view of the machine;

FIG. 7 is a detail sectional view of the sine bar unit shown in outline in FIG. 5; I

FIG. 8 is a horizontal sectional view through the sine bar unit as taken substantially along the line 8-8' in FIG. 7; 7

FIG, 9 is a somewhat schematic fragmentary view showing the hairline indicator and dial of the sine bar unit; and

FIG. 10 is a top view of the sine bar unit.

Referring now in greater particularity to the drawings, and first to FIG. 1, there will be, seen a helical lead checking machine designated generally by the numeral 20, and comprising a base 22. A table 24 is mounted on the base for longitudinal movement thereon by means of ball bearings 26 (see FIGS. 5 and 6).

The headstock 28 is mounted on the table 24, and a tailstock 30 is mounted on the table adjacent the opposite end (thereof. The tailstock 30 is mounted on the table by means of the usual dovetail guideways 32, suitable locking means being provided for fixing the tailstock in adjusted position, and the tailstock preferably is vertically and horizontally adjustable. The tailstock center 34 is axially adjustable by means of a screw thread arrangement actuated by a handwheel 3 6, in accordance with conphantom lines 117) having an apex 119 located on the ventional practice.

ICC

A subbaser38 extends upwardly in front of the table,

and is provided with a-guideway 40 mounting a cross slide 42 for movement parallel to the table 24.

A checking device 44 is mounted on the cross slide for movement transversely of the table. The checking device is of a type known in (the art, and includes a screw-' threaded device 46 for moving the checking device along the' cross slide 42. The checking device also includes a pivotally mounted checking or pickup finger 48 which is pivotally mounted to actuate an indicator 50. This checking finger also preferably operates anel-ectrical dee. vice for operating a remote recorder, all as is known in the art.

The headstock 28 is of generally known construction and as shown in FIGS. 2 and 3 includes a housing 5-2 in which a spindle 54 having a center 56 and dog 58 is journaled by means of ball bearings 60. A horizontal cross slide 62 is mounted below the spindle, preferably by means of ball bearings 64, for movement transverse of the table and of the spindle. Steel bands 66 are fixed to the spindle 54 at 68, and are partially wrapped around thespindle, and lie along the top of the horizontal cross slide, being secured thereto at the opposite sides as at 70. As will be apparent, when the cross slide is moved horizontally transverse of the spindle 54, it will act through the flexible steel bands 66 to rotate the spindle proportionally to the distance the cross slide is moved.

The horizontal cross slide 62 is provided with a depending stud 72 on which there are sine ba-r followers 74.

Referring now in greater particularity to FIGS. 5 and 7-10, there will be seen the sine bar, mechanism or assembly generally designated by the numeral '76. The sine bar assembly includes a housing 78 bolted to the machine base 22 as at 80. A sine bar 82 is provided at the top of the assembly, and has a slot or grooves 4 in the top surface thereof. The sine bar 82 is provided with a raised shelf portion providing a surface or edge 86 co operable withthe upper one of the sine bar followers 74, while a lower sine bar guiding surface or edge 88 cooperates with the lower one of the followers 74. Thus, a

firm fit is assured Without any play, but allowing proper rotation Ofthc-followers 74'. In this connection, it will beobserved thatuthe raised table is undercut as at 90 below the guiding surface 86 to provide clearance for the lower follower 74; i

-Thesine bar'82 is bolted as at 92 to the upper end of a 4 cylinder or sleeve 94.journaled at axially spaced locations in ball bearings 96 received in a suitable aperture-in the housing-7 8. Thecylinder or sleeve 94 is provided near its lower end with an external annular flange 98. A gear100 ofthe type normally sold under the registered trademark Spiroid is bolted to this flange as at 102. The Spiroid gear 100 is of the type disclosed in Saari Patent 2,696,125 A complementary Spiroid worm 104 meshes with this gear, and is fixed on a shaft 106 journaled in ball bearings 108 in a cylindricalrextension 110 of the housing 78. Thus the gear 100 connected to the sine bar 82 is, as disclosed in Patent No. 2,696,125, a face-type worm gear having teeth 105 mating with the Worm 104. The teeth 105 are shaped to have side faces which engage the thread 107 of the worm throughout substantially the entire areas of the respective side faces of the teeth mating with the worm. The worm 104 has a frusto-conical form, which is rec tilinearly and moderately tapered. The worm thread 107 has a constant axial lead and has sufficient extent to form a plurality of complete thread convolutions. The mutually engaged meshing portions of the worm 104 and gear 100 are locatedon one side of a common perpendicular 109, FIG. 8, to the axis 111 of the wodm and the axis 113 of the gear. The root surface 115 of the worm conforms to and is contiguous with a cone (illustrated in FIG. 8Iby side of the common perpendicular 109 opposite from the previously mentioned mutual engagement of the gear 100 and worm 104. Put another way, the cone apex 119 and the mutual engagement of the worm and gear are located on opposite sides of a plane coincident with the gear axis 113 and substantially normal to the worm axis. This plane contains the common perpendicular 1 09 and is represented in FIG. 8 by the same line 109. The shaft 106 is provided with an extension 112 journaled in ball bearings 114 in an inwardly projecting cylindrical section 116 of the housing 78. The outer end of the extending shaft 112 is provided with a pulley 118 driven by a belt 120, as hereinafter will be described. The shaft extension 112 is coupled to the shaft 106 by means of a suitable clutch means at as 122.

The outer end of the shaft 106 is provided with a handwheel or knob 124 having a peripheral scale 126 thereon. The gear and pinion 100, 104 have a reduction ratio of 360 to 1. Hence, for one revolution of the worm, one de gree of rotation is imparted to the gear 100. The scale 126 is provided with 360 graduations, and in conjunction with the 360 to 1 reduction ratio, each graduation is equal to ten seconds. A Vernier 128 is provided adjacent the scale 126, and allows the operator to read within one second of angular arc.

Fine readings are provided by the scale 126 and vernier 128 as just indicated. Coarse readings are provided by a scale 130 fixed about the periphery of the gear 100. A window is provided in the housing 78 for reading the scale 130, and a hairline 132 is provided in this window.

To facilitate reading the scale 130, an optical reading device 134 is provided on the side of the base 22. This device, as shown generally in FIG. 1, and specifically in FIG. 4, comprises a right angle housing 136 mounting a right angle prism 138. A window 140 is provided at the top of the optical reading device, and an operator looks down into this window, and sees the reflected image of the scale 130 and hairline 132 through the prism 138. To facilitate reading, the zero line on the scale 130 is provided two inches off center, and the graduations on the scale 130 are inverted and reversed in progression about the gear.

As has been noted, the cylinder or sleeve 94 is journaled in ball bearings 96. As will be observed in FIG. 7, a hearing pull down ring 142 is bolted to the top of the housing 78 as at 144, and has a depending skirt portion 146 bearing on top of the outer race of the upper bearing 96. An inwardly projecting annular lip 148 in the housing 78 supportsthe outer race of the lower bearing 96, and cylindrical beating spacers 150 are respectively positioned between the outer races and the inner races of the upper and lower bearings 96.

A drawbar 152 extends upwardly through a vertical projection or boss 154 in the interior of the housing 78, being journaled in sleeve bearings 156 adjacent the top and bottom. The drawbar is provided with a reducedlower end connected to a clevis 158 at the top of an operating member 160 hereinafter to be described in greater detail. The drawbar 152 is formed at its upper end with a circular plate 162, and a circular retracting member 164 peripherally undercut at 166 is secured to the top of the plate 162 by means of bolts 167.

The upward projection 154 in the housing 78 is provided adjacent its midsection with a circumferential rib 168 positioning the lower end of the cylinder of sleeve 94, and above this rib there is a frusto conical section 170. An additional frusto conical section 172 is provided at the top of the projection 154.

A vertically split locking member 174 lies between the upper end of the projection 154 and the cylinder or sleeve 94. The locking member 174 is generally cylindrical, but is provided with frusto conical sections 176 and 17 8 which are respectively complementary to and cooperative with the frusto conical surfaces or sections 170 and 172.v The split locking element or member 174 extends above the frusto conical section 178, and is provided with an inwardly directed annular lip 180 lying above the plate 162 and below the retracting member 164.

As will be apparent, when the drawbar 152 is raised, the plate 162 pushes up beneath the lip 180, and thus raises the locking element 174 slightly, in order to prevent the frusto conical sections 176 and 178 from wedging against the corresponding frusto conical sections 170 and 172. Conversely, when the drawbar 152 is pulled down, the retracting member 164 presses down on top of the locking element 174, and forces the aforesaid frusto conical sections into wedging engagement. The gear thus is firmly locked relative to the housing 78, and the sine bar 82 is fixed in any position of adjustment.

Referring now to FIG. 5, there will be seen a lever 182 (see also FIG. 1) pivoted on the side of the machine base 22. The lever is fixed on a shaft 184 extending into the base, and a short lever 186 is fixed on the shaft within the base. A connecting rod 188 is pivotally connected to the end of the lever 186, and also to a lever 190 pivoted intermediate its ends at 192 on a fixed part 194 of the machine. The opposite end of the lever 190 is received between plates 196 mounted on a stud 198 forming a part of the operating member 160. Springs 200 and 202 are respectively compressed between the plates 196 and the clevis 158, and a nut 204 threaded on the lower end of the rod 198. Thus, whenever the lever 182 is manually actuated the gear .100 is either locked or unlocked. Specifically, when the lever 182 is thrown all of the way to the left, the gear is unlocked, and when the lever 182 is as far to the right as it will go, the gear is locked.

A motor and gear drive unit 206 is mounted within the machine base, and is provided with an output pulley 208. The output pulley 208 drives the belt passed over the pulley 118. The motor an gear drive mechanism 206 is of known construction, and includes a double acting clutch having a shifter fork 210 for shifting the clutch from neutral in either direction, the pulley 208, and hence the belt 120, being driven in opposite directions according to the direction in which the shifter fork 210 is moved from the neutral position. The shifter fork is mounted for movement about a vertical pivot 212, and a lateral arm 214 on this pivot is connected by a connecting rod 216 to a lever 218 within the machine base. The lever 218 is fixed on a pivot shaft 220 extending through the base to the outside thereof, and a handle or lever 222 is fixed on the shaft 220 exteriorly of the base.

A switch (not shown) is associated with the shaft 220, and is normally open. The switch is closed whenever the shaft is rotated in either direction from the neutral position with the handle or lever 222 extending straight up. Thus, when the handle or lever 222 is thrown in either direction, the switch will be actuated, and the motor 206 will thereby be energized. Simultaneously, the clutch will be closed in either direction by the shifter fork 210 to drive the pulley 208 and belt 120 in either direction. Correspondingly, the pulley 118 will be driven, and accordingly the worm 104, and hence the gear 100 will be driven, whereby to rotate the sine bar 82 to a. desired position of adjustment.

Referring now to FIGS. 1, 5 and 6, there will be seen a handwheel 224 positioned at the front of the machine. The handwheel is fixed on a shaft 226 extending through a horizontal slot 228 in the table 24. The shaft 226 is journaled as in a sleeve bearing 230 in the sub-base 38, and in bearings 232 in a gear box 234 at the back of the machine. A helical pinion or worm 236 is fixed on the shaft 226 within the gear box 234, and rotates a larger helical gear 238. The gear 238 in turn drives a helical gear 240 mounted on a shaft 242 and acting through a suitable clutch mechanism (not shown) to drive this shaft. The shaft 242 is journaled in a bearing 244 in the gear box, and in a bearing 246 adjacent the opposite end of the shaft, and adjacent the centerline of the machine. A

pinion 248 is fixed on the end of the shaft 242, and meshes with a rack 250 depending from the table. A third handle or lever 252 is fixed on the front of the machine base and acts through a cross shaft 254 and a universal joint 256 to actuate the clutch (not shown).

When the clutch is closed in one position, the handwheel 224 can be rotated, and operates through the gearing 236, 238, 240, to cause the pinion 248 to drive the rack 250, for longitudinally shifting the table 24. This structure is known in the art, and hence is not shown in great detail. When the handle 252 is thrown in the opposite direction, it preferably causes further known mechanism (not shown) to operate whereby the cross slide 62, rather than the table, acts as the prime mover.

Operation A workpiece, such as a helical gear, not shown herein, is mounted between the headstock and tailstock centers in accordance with conventional practice. The sine bar is set by first releasing the machine drive mechanism by means of the lever or handle 252, so that the drive is in neutral position. Next, the sine bar locking mechanism is released by moving the handle or lever 182 all of the way to the left.

The next step is to rotate the sine bar to the proper degree setting through the use of the lever or handle 222, controlling the motor 206 and drive connections to drive the worm rapidly, whereby to effect a rapid coarse setting of the gear and sine bar. The angular position of the gear is read through the optical reading device 134 to line up the scale 130 relative to the hairline 132. The final accurate or fine setting is effected by manually turning the knob 124 and utilizing the scale 126 and vernier 128. The sine bar then is locked in position by means of the lever or handle 182, and the handle 252 is operated to connect the drive part so that the handwheel 224 will be efiective to drive the table.

As the table is shifted longitudinally of the machine, the sine bar followers 74 are forced in one direction or the other by the sides of the sine bar groove 84. This shifts the transverse cross slide 62 transversely of the machine, and causes rotation of the headstock spindle proportionate to the axial shifting thereof relative to the table. As has been noted heretofore, the position of the sine bar can be read to within one second of angular arc. This is done in an assembly or unit not more than a foot or two in any dimension. In accordance with conventional practice, a scale of twenty feet or so in diameter would be necessary to attain this accuracy and this would obviously be a prohibitive size for checking a gear of perhaps three inches in diameter. In spite of the extreme reduction ratio of the gearing for adjusting the sine bar, adjustment is extremely rapid. The rapidity of adjustment stems from the motor driven initial adjustment, and the extreme case of reading the final adjustment as effected manually. The Spiroid gears used in the gear reduction unit of the sine bar assembly are of extreme importance. These gears are totally without backlash, and it will be appreciated that backlash cannot be tolerated in any device reading as closely as the one herein. The reduction ratio, as previously noted, is 360. 1. There are approximately thirty-two teeth in simultaneous contact at all times, thus insuring a smooth driving action, free of backlash.

It is to be understood that the specific embodimentof the invention as herein shown and described is for illustrative purposes only. Various changes in structure will no doubt occur to those skilled in the art, and areto be understood as forming a part of this invention in so far as they fall within the spirit and scope of the appended claim.

The invention is claimed as follows:

In a machine of predetermined length and having a mid-point for checking the lead of a helical surface, said machine having a front side, the combination of support means for rotatably supporting a helical surface defining object, surface position sensing means, movable means for effecting translation of said support means in a first linear direction relative to said sensing means, a sine bar, means supporting said sine bar for rotation about an axis perpendicular to both said sine bar and said linear direction, a sine bar follower mounted for translation in a second linear direction perpendicular to said first linear directiommeans for rotating an object in said support means, means interconnecting said object rotating means with said follower for operation by movement of the latter in said second direction, means connecting said movable means with said follower to move the latter in said first linear direction simultaneously with and proportionately to translation of said support means relative to said sensing means, a face type worm gear having an axis and connected to said sine bar to rotatably position the latter about the axis thereof, a rectilinear-1y and moderately tapered worm rotatably about a second axis having a plurality of complete thread convolutions of constant axial lead mating with said gear, said gear having teeth defining side faces which engage the thread of the worm throughout substantially the entire areas of the respective side faces, said worm having a root surface contiguous to a cone the apex of which is located at the side of a common perpendicular to the axes of said worm and gear opposite from the mutual engagement of the worm and gear, power means for rotating said worm about said second axis, means on said front side of said machine for selectively controlling said power means, a manual actuator located on said front side of said machine for rotating said worm about said second axis, said second axis of the worm being located closer to the midpoint of said machine than said axis of said face gear, a graduated scale associated with said worm for indicating the angular position of said sine bar, and a graduatedscale associated with said gear for indicating the angular position of said sine bar, optical reading meansincluding a hairline on said front of said machine for indicating the angular position of said gear, releasable locking means accessible to and located on the front of said machine for selectively locking said sine bar in desired position after adjustment thereof, said worm being the sole adjustment for locating the position of said gear and sine bar, and the axis of said worm being so arranged such that the manual actuator for rotating said worm about its axis is readily accessible by an operator standing adjacent to the midpoint of said machine.

References Cited in the file of this patent UNITED STATES PATENTS 

